HUMAN beings are social animals. But just as important, we are socially constrained as well.

We can probably thank the latter trait for keeping our fledgling species alive at the dawn of man. Five core social instincts, I have argued, gave structure and strength to our primeval herds. They kept us safely codependent with our fellow clan members, assigned us a rank in the pecking order, made sure we all did our chores, discouraged us from offending others, and removed us from this social coil when we became a drag on shared resources.

Thus could our ancient forebears cooperate, prosper, multiply — and pass along their DNA to later generations.

But then, these same lifesaving social instincts didn’t readily lend themselves to exploration, artistic expression, romance, inventiveness and experimentation — the other human drives that make for a vibrant civilization....